U.S. patent number 6,160,353 [Application Number 09/389,719] was granted by the patent office on 2000-12-12 for remote positionable photocell device for use with an exterior landscape lighting assembly.
Invention is credited to Michael L. Mancuso.
United States Patent |
6,160,353 |
Mancuso |
December 12, 2000 |
Remote positionable photocell device for use with an exterior
landscape lighting assembly
Abstract
A photocell device for use with an exterior landscape lighting
assembly. The lighting assembly includes a transformer having an
input line connected to an electrical power source. The transformer
converts a primary electrical load to a secondary electrical load
which is in turn outputted through an output line connecting to a
plurality of individual lighting units. The photocell device is
capable of being mounted at an appropriate exterior location, such
as to the side of a building structure. An enclosure unit includes
a power supply circuit, a photo sensor and control circuitry
communicating with the photo sensor. At least one light permissive
window is formed within a selected front facing and/or top facing
surface of the enclosure unit. The power supply circuit converts
the secondary transformer output to an unregulated and filtered
direct current suitable for powering the control circuitry. The
control circuitry interfaces with the photo sensor and, in response
thereto, selectively activates and deactivates the plurality of
lighting elements. The control circuitry further includes such
features as timer and dimmer capability and also may include
software algorithmic capability for receiving a selected real time
input signal and operating the lighting units responsive to the
input signal.
Inventors: |
Mancuso; Michael L. (Milford,
MI) |
Family
ID: |
46255637 |
Appl.
No.: |
09/389,719 |
Filed: |
September 3, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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099559 |
Jun 18, 1998 |
5962982 |
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Current U.S.
Class: |
315/159; 250/205;
315/316; 315/324 |
Current CPC
Class: |
F21V
21/0824 (20130101); H05B 47/11 (20200101); H05B
47/16 (20200101); Y02B 20/46 (20130101); Y02B
20/40 (20130101); Y02B 20/42 (20130101) |
Current International
Class: |
H05B
37/02 (20060101); H05B 037/02 () |
Field of
Search: |
;315/149,152,276,156,158,159,292,316,324 ;250/205 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Intermatic Brochure--Outdoor Lighting Timer. .
Brochure on Malibu Plug-In Power Pack. .
Brochure on Malibu Remote Photo Control, all dated 1 year prior to
applicant's invention. .
Vista Brochure on Transformers Vista Professional Outdoor
Lighting--Brochure (Night Guard Series). .
Power Centers & IQ Controller--Brochure First Alert
Brochure--Automatic Outdoor Light Timer, all dated 1 year prior to
applicant's invention..
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Primary Examiner: Philogene; Haissa
Attorney, Agent or Firm: Gifford, Krass, Groh, Sprinkle,
Anderson & Citkowski, P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of U.S.
application Ser. No. 09/099,559, Filed Jun. 18, 1998 now U.S. Pat.
No. 5,962,982 for a Remote Photocell Device for use with an
Exterior Landscape Lighting Assembly.
Claims
I claim:
1. A photocell device for use with an exterior landscape lighting
assembly, the lighting assembly including a transformer having an
input line connected to an electrical power source and an output
line connecting to a plurality of individual lighting units, the
transformer converting the power source from a primary electrical
load through the input line to a secondary electrical load through
the output line, said photocell device comprising:
an enclosure unit including a power supply circuit, a photo sensor
and control circuit means operatively communicating with said photo
sensor;
means for supporting said enclosure unit at an outdoor and light
receiving location; and
said photocell device electrically communicating with the output
line at a point remote from the transformer and prior to a first of
the plurality of individual lighting units, said power supply
converting the secondary load to an unregulated and filtered direct
current suitable for powering said control circuit means, said
control circuit means selectively activating and deactivating the
secondary electrical load to said plurality of individual lighting
units.
2. The photocell device according to claim 1, further comprising an
elongate and transparent rod extending upwardly from said enclosure
unit, said rod serving as a light conduit to transmit ambient light
to said photo sensor.
3. The photocell device according to claim 1, further comprising
the transformer output being provided at 12 V AC.
4. The photocell device according to claim 1, said control circuit
means further comprising a light control circuit incorporating said
photo sensor, a Schmitt trigger introducing a dead band into said
light control circuit to prevent activation and deactivation of
said secondary electrical load within specified parameters.
5. The photocell device according to claim 4, said control circuit
means further comprising a dimmer circuit for establishing a degree
of illumination of the lighting units.
6. The photocell device according to claim 4, said control circuit
means further comprising a timer circuit for establishing an off
time for deactivating the secondary electrical load to the lighting
units.
7. The photocell device according to claim 1, said means for
supporting said enclosure unit further comprising means for
securing to an exterior facing and light receiving surface of a
building.
8. The photocell device according to claim 7, further comprising a
plurality of fasteners for securing said enclosure unit to the
facing surface of the building.
9. The photocell device according to claim 1, further comprising a
light transmissive window formed within at least one of a forward
facing and top facing surface of a building to serve as a light
conduit for transmitting ambient light to said photo sensor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to exterior landscape
lighting assemblies having a specified form of photocell control
and, more particularly, to a remote positionable photocell device
capable of being located a spaced distance from a transformer and
further capable of providing a unique array of photocell controls
to a plurality of exterior lights.
2. Description of the Prior Art
The prior art is well documented with outdoor landscaping lighting
assemblies and, particularly, lighting assemblies which utilize
some form of photocell control for activating and deactivating the
outdoor lighting based upon day and night conditions. Generally all
landscape lighting systems are powered by 12 volts (V) alternating
current (AC) by means of a transformer which converts an AC
household power input (typically 120 V AC) to the 12 Volts AC
suitable for this type of lighting. The transformer is a necessary
component owing to the power input specifications of the various
lighting elements which make up the landscaping lighting
assembly.
Establishing on/off control of landscape lighting systems has
traditionally been accomplished in a number of different ways,
these including installing a timer on the primary winding of the
transformer. The shortcoming however with simple timer assemblies
is that they require frequent readjustment, particularly following
power outages and further that the transformer must be located in
an area accessible to the user in order to make the necessary
adjustments.
Other types of prior art assemblies include installing a photocell
on the exterior of the transformer case and communicated with the
primary winding of the transformer. In this variant, the
transformer must be mounted on the exterior wall of the home or
structure around which is surrounded the lighting assembly. The
transformer must be conspicuously located near an available
exterior covered ground fault interrupted outlet where the
photocell is exposed to natural light (preferably a Northern
exposure) and without direct exposure to street lights, porch
lights, car headlights and other lights which are directly
controlled by the transformer. The drawback of this variant is that
most homeowners do not desire having the transformer or any other
device located on the exterior of their home in an exposed
position. Also, the availability of a suitable outlet at the
necessary location for proper functioning of the photocell is
likewise often a problem.
SUMMARY OF THE PRESENT INVENTION
The present invention is a photocell device for use with an
exterior landscape lighting assembly which overcomes the
shortcomings of the prior art by providing the photocell device as
a separably positionable unit apart from the transformer and which
permits the device to be mounted at any suitable outdoor location
for selectively activating and deactivating a plurality of lighting
units. By separating the photocell device from the transformer, the
transformer may be located anywhere without consideration to
sunlight access or timer accessibility. In most instances, this
means that the transformer need no longer be located externally of
the residence or other structure around which the lighting elements
are located.
The photocell device includes a turf stake capable of being engaged
into a ground location and an enclosure unit mounted atop the turf
stake. The enclosure unit includes a power supply circuit, a photo
sensor element and control circuitry operatively communicating with
the photo sensor. The control circuitry includes such elements as a
light sensor, schmitt trigger, and load break. Algorithmic software
circuitry may also be incorporated into the control circuitry for
the purpose of receiving internally programmed or externally
transmitted real time signals, such as by means of a suitable
antenna, and for activating and deactivating the load to be sent to
the lighting units.
The power supply circuit converts the secondary load of the
transformer into an unregulated and filtered direct current
suitable for powering the control circuitry. The control circuitry,
in response to receiving an appropriate input from the photosensor,
selectively activates the lighting units and the duration and
intensity of the load may further be established by such additional
features as timer circuitry and dimmer/brightness circuitry.
In a preferred embodiment, the enclosure unit which includes the
photo sensor and associated circuitry also includes an open or
transparent covering over the photo sensor and which is formed on a
selected face. In a further preferred embodiment, a clear rod
extends upwardly from the electrical enclosure unit and functions
as a light conduit for transmitting ambient light to the photo
sensor which is mounted in the electrical enclosure directly below
the clear rod access hole. In a still further embodiment, the
electrical enclosure unit incorporates a transparent or light
permissive window with the photocell assembly being positioned in
proximity to an inner face of the window within the unit. The
window is capable of being arrayed upon a selected forward or top
facing surface of the enclosure unit.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to the attached drawings, when read in
combination with the following specification, wherein like
reference numerals refer to like part sthroughout the several
views, and in which:
FIG. 1 is an environmental view in perspective of the photocell
device for use with an exterior lighting assembly according to a
preferred embodiment of the present invention;
FIG. 2 is an is an exploded view of the photocell device
illustrated in FIG. 1 and according to the present invention;
FIG. 3 is an enlarged view in cutaway of the clear rod extending
upwardly from the electrical enclosure unit and in proximity to the
photo sensor element according to the present invention;
FIG. 4 is a perspective view of a photocell device according to a
further preferred embodiment of the present invention;
FIG. 5 is a perspective view of a photocell device according to a
yet further preferred embodiment of the present invention;
FIG. 6 is a view of a menu display for the photocell device which
references the power supply and control circuitry according to the
present invention;
FIG. 7 is a schematic view of load relay switches AC HOT power on
and off to control any load connected between AC SWITCHED and AC
NEUTRAL positions and according to the control circuitry of the
present invention;
FIG. 8 is a control schematic of the power supply, photocell and
control circuitry according to the photocell device of the present
invention;
FIG. 9 is a schematic view of an optional timer control subsystem
capable of interfacing with the control circuitry according to the
present invention;
FIG. 10 is a schematic view of an optional dimmer control subsystem
capable of interfacing with the control circuitry according to the
present invention;
FIG. 11 is a schematic view of an optional real time broadcast
receiver/timer circuit capable of interfacing with the control
circuitry according to the present invention;
FIG. 12 is an environmental view in perspective of the photocell
device according to a still further preferred variant of the
present invention;
FIG. 13 is an exploded view of the photocell device according to a
further variant of the present invention; and
FIG. 14 is a schematic of the transistor incorporating the control
circuitry according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, an environmental view is shown of a
photocell device 10 for use with an outdoor lighting assembly
according to a preferred embodiment of the present invention. The
photocell device 10 is illustrated in use with an electrical
transformer 12, a first outdoor lighting unit 14 and a second
outdoor lighting 16 unit. The transformer 12 is illustrated placed
upon an exterior facing surface of an outside wall 18 of a
structure 20 however, as explained in the preceding summary of the
invention, the provision of the photocell device 10 with integral
circuitry enables the transformer 12 to be mounted at any location
inside or out of the structure 20 without consideration to sunlight
access or timer accessibility. As is also known, the transformer 12
functions to convert an input power source from a primary
electrical load (typically 120 Volt AC household power) to a
stepped down 12 Volts AC suitable for most types of conventional
outdoor lighting assemblies. The transformer 12 also includes an
input line (not shown) connected to the electrical power source and
an output line, illustrated at 22. The photocell device 10
communicates with the output line 22 of the transformer 12 at any
desired point between the transformer 12 and a first of the
lighting units 14 and 16.
Referring again to FIG. 1 and also to FIG. 2, the photocell device
10 is again shown and includes a turf stake 24 which, as is best
shown in FIG. 1, is capable of being engaged into a ground
location. The turf stake 24 can be of any desired construction but,
as is illustrated, preferably includes a plurality of downwardly
and tapering projections 26 which narrow to a point 28. Located at
a top end of the stake 24 opposite the point 28 is an externally
threaded screw projection 30 which is capable of being threadably
engaged into a corresponding internally threaded recess 32 located
on a bottom face of an enclosure unit 34.
Referring again to FIG. 2 and also to FIG. 3, the enclosure unit 34
is generally rectangular shaped and includes an interior cavity for
receiving control circuitry for operating the device 10, as will be
subsequently described in more detail. Located proximate a top of
the enclosure unit 34 is a photo sensor element 36, such an element
by itself being according to a construction known in the art for
signalling changes in light correlating to daytime and nighttime
periods. The photo sensor element 36 is mounted in proximity to an
aperture in the top face of the enclosure unit 34, the aperture
being defined by an interiorly recessed threaded wall 38.
An elongate and transparent rod 40 is provided and includes a
downwardly extending and exteriorly threaded end 42 which is
threadably interengaged with the interiorly recessed and threaded
wall 38 of the enclosure unit 34. The function of the transparent
rod 40 is to gather light from all directions surrounding the
photocell device 10 once it is implanted into the ground, this
enhanced ability to gather light making the placement and
orientation of the device less critical than other prior art
designs. The rod 40 acts as a light conduit to transmit ambient
light to the photo sensor 36 mounted in the electrical enclosure 34
directly below the aperture formed by the recessed threaded wall
38. Advantages of the elongate and transparent rod 40 include the
ability to extend above anticipated height of and snow
accumulation, thus keeping the enclosure low to the ground and out
of plain sight. The very small horizontal surface area of the rod
40 also serves to prevent leaves and other yard debris from
accumulating and obstructing ambient light from reaching the photo
sensor. The rod 40 may also serve to calibrate the photo sensor 36
by applying black electrical tape to cover a specified circular
area of the rod 40.
Referring to FIGS. 4 and 5, additional variants of photocell
devices are illustrated at 44 and 54, respectively. Addressing
first the variant of FIG. 4, the photocell device 44 includes a
turf engaging stake 46, an upwardly extending stem portion 48 and
an enclosure unit 50 mounted atop the stem portion 48. A photo
sensor element 52 is positioned upon a forward face of the
enclosure unit 50 and, upon proper orientation of the photocell
device 44 in a suitable outdoor location, gauges the degree of
available light. Referring further to the variant of FIG. 5, the
photocell device 54 includes again a turf stake 56, an enclosure
unit 58 integrally formed with the turf stake 56, and an elongate
and transparent rod 60 (same as illustrated at 40 in FIGS. 1-3)
which threadably engages with the enclosure unit 58 and which is
arranged proximate to a photo sensor element (not shown) which is
arrayed within the unit 58 underneath the connection with the rod
60. Aside from their differences in construction, the photocell
devices 44 and 54 operate in identical fashion with the photocell
device 10 illustrated in FIGS. 1-3 and each further includes
appropriate input and output lines to interconnect with the
transformer output line 22 such as is shown by the device 10 in
FIG. 1.
Referring now to FIG. 6, a menu display is illustrated at 62 which
illustrates the basic operating components of the control circuitry
incorporated within the enclosure unit of the photocell device. The
menu display includes a power supply indicating touch pad 64 for
turning the unit off and on. A second control circuit touch pad is
illustrated at 66 and controls such circuitry functions as the
light sensor for measuring levels of light and for activating a
specified electrical load, a schmitt trigger for introducing a dead
band into the light control circuit and for preventing the circuit
from rapidly turning on and off as a result of only minor changes
in light level (line chatter), optional timer and dimmer circuits
and, finally, a load control/breaker circuit for providing power to
the load relay and transient voltage protection to the control
circuitry. A more detailed explanation of operation of the control
circuitry of the photocell device of the present invention will be
had with reference now to the various schematic views of FIGS.
7-11.
Referring to FIG. 7, a schematic view is shown at 68 of the
switching array for the transformer output. Specifically, the 12 V
AC output of the transformer (indicated at 70) enters the AC HOT
and AC NEUTRAL terminals 72 and 74 of the power supply and is
converted to an AC SWITCHED load at 76 suitable for illuminating
the individual lighting units, illustrated schematically at 78.
Referring to FIGS. 8 and 14, respective schematic and circuit card
views are illustrated of the operation of the basic control
circuitry of the photocell device according to the present
invention. The schematic is particularly illustrated at 80 in FIG.
8 and at 81 in FIG. 14. At 82, 84, 86 and 88 are shown first,
second, third and fourth diodes in full wave rectifying the
incoming 12 V AC signal from the secondary load of the transformer.
A capacitor 90 (ideally set at 100 micro-Farads at 25 Volts)
filters the rectified AC signal to develop filtered and unregulated
DC which serves as the power supply for the control circuitry.
The photo/light sensor is illustrated as CDS photocell PC1 element
92 and combines with a first resistor 94 to determine a preset
light level in which to activate the electrical load either on or
off by biasing a base of a transistor Q1 96. The schmitt rigger,
formed by first transistor Q1 96 and a second transistor Q2 98 as
well as a second resistor 100 (preferably 10 K-Ohm at 1/4 Watts)
and a third resistor 102 preferably 1.2 K-Ohm at 1/4 Watts),
functions by introducing a hysterisis to the witching circuit to
prevent relay chatter as previously described.
Assuming a predetermined level of darkness is obtained, the first
transistor 96 will be biased such that it is off. The base of the
second transistor 98 is biased by the voltage divider consisting of
the resistors 100 and 102. If the input voltage falls below the
switching level of the circuit, the first transistor 96 remains off
and the relay on. As the input voltage approaches the calibrated
switching voltage, a critical voltage is reached where the first
transistor 96 begins to conduct and regeneratively turns off the
second transistor 98 and relay 100. If the input voltage is lowered
below a second critical level, the second transistor 98 will again
conduct, switching the relay 101 on.
A fifth diode 102 is located in proximity to the relay and protects
the control circuit by clamping voltage spikes generated by the
coil of the relay 101. The relay 101 is appropriately sized to
carry the large amount of current necessary to control the
secondary load of the transformer and the 12 V AC switched load
(for supplying the lighting elements) is again illustrated
schematically at 76 in communication with the output of the relay
101. Likewise, the 12 V AC HOT and 12 V AC NEUTRAL inputs are also
illustrated again at 72 and 74 in operative communication with the
power supply (diode relay 82-88) for supplying the input secondary
load from the transformer.
Referring now to FIG. 9, an optional timer circuit is illustrated
at 104 and is capable of being used with the basic operating
circuit of FIG. 8. The photocell element is again illustrated at 92
and is separated from the voltage input by a third resistor 106
(ideally set at 150 K-Ohm). The light sensor 92 communicates with a
control integrated circuit 108. The control integrated circuit 108
is powered by converting the unregulated DC voltage established by
the power supply control circuit into a 5 V regulated DC supply,
illustrated at 110. The power supply circuitry otherwise operates
in the same manner illustrated in FIG. 8 with the further exception
that a further capacitor 111 filters the half wave rectified AC and
converts it to the unregulated DC. The unregulated DC is the
potential needed to turn the relay 101 on and off and is fed to one
side of the load relay coil. A diode 112 provides transient voltage
protection to the remainder of the circuit 104.
The control integrated circuit 108 includes an input 114 which
monitors a 60 Hertze AC frequency and utilizes this signal to
generate an accurate time base. A second resistor 116 is inserted
between the AC HOT terminal 72 and the input 114 to limit the
current flow and to protect the integrated circuit 108. Output
terminal 118 is connected to the output of the first transistor 96
and is separated by a resistor 120. The output of terminal 118
controls the load relay 100 which in turns the lights on and off
via the base resistor 120 and first transistor 96. The resistor 120
limits the base current of the first transistor 96 that provides
the drive current necessary to energize the load relay 101. Light
and darkness levels are sensed by the photo sensor 92 and are fed
into a further input 122 of the circuit 108 to provide a dead band
into the circuit, much like the schmitt trigger previously
described. The third resistor 106 is used to calibrate the amount
of light needed to activate the input 122.
Inputs 124, 126 and 128 of the integrated circuit 108 sense a
desired mode of operation of the unit 108 and can be programmed by
the user via a switch 130 to effect up to eight different odes of
operation. This is further referenced by mode programs 132 which
are in effect timing selections for the period of running operation
of the device such as 2 hours, 4, hours, 6 hours, 8 hours, etc.
Additional resistors 134, 136 and 138 are disposed between the
switch 130 and the circuit inputs 124, 126 and 128, respectively,
and limit current and multiplex or share of these inputs to allow
the circuit to be serially programmed at the factory via a
connector 140.
Closely related to the timer schematic of FIG. 9 is a further
dimmer schematic of FIG. 10 illustrated at 142. The dimmer
schematic represents many of the elements schematically described
in the timer circuit of FIG. 9, and discussion will therefore be
limited to the elements of the dimmer circuit. The control
integrated circuit is again referenced at 108 and, in this
instance, the output 118 controls the duty cycle to the gates of
four Amp triacs 144, 146, 148 and 150 which are connected in
parallel and which provide a 40 Amp output to the load. Once again,
inputs 124, 126 and 128 are again used to sense the desired modes
of operation of the unit 108 and can be programmed by the user via
switch 130. Illustrated at 132' is a further table of varying
brightness levels associated with the dimness mode program.
Connector 140 is again illustrated for enabling programming of the
unit 108 at the factory.
Referring to FIG. 11, a further variation of the present invention
presents a schematic 152 illustrating a real time broadcast
receiver/timer circuit for use with the basic control circuitry and
according to a further preferred variant of the present invention.
As with the timer and dimmer circuit schematics of FIGS. 9 and 10,
the real time circuit of FIG. 11 largely represents the same
elements and attention will therefore be limited to those which are
unique to this feature.
Specifically, a ferrite rod antenna 154 is arrayed such that it is
communicating with a further integrated circuit 156 capable of
receiving and decoding an appropriate broadcast signal emanating
from a remote source. In a preferred embodiment, the broadcast
signal may be transmitted as a shortwave signal and originate from
a location accessible to most or all parts of the United States.
Such a transmitting location is ideally Boulder, Colo. where a 60
kHz broadcast signal may be sent out. The decoded signal is
serially fed to input 128 of the control integrated circuit 108
through the current limiting resistor 120. A quartz crystal 158
sets the receiver frequency and capacitors 160, 162, 164, 166 and
resistor 168 adjust the gain, bandwith, sensitivity and selectivity
of the receiving circuit.
Referring to FIG. 12, a similar environmental view is shown at 170
of a photocell device 172 for use with an outdoor lighting assembly
according to a further preferred embodiment of the present
invention. Similar to FIG. 1, the photocell device 172 is
illustrated in use with an electrical transformer 174, a first
outdoor lighting unit 176 and a second outdoor lighting 178 unit.
The transformer 174 is illustrated placed upon an exterior facing
surface of the outside wall 18 of the structure 20 and, as
previously described, functions to convert an input power source
from a primary electrical load (typically 120 Volt AC household
power) to a stepped down 12 Volts AC suitable for most types of
conventional outdoor lighting assemblies. The photocell device 172
according to this embodiment is secured to the exterior facing
surface 18 of the structure 20, such as by fasteners shown at 180,
and as an alternative to the use of the ground stakes illustrated
in the embodiments of FIGS. 2, 4, and 5. Alternatively, other types
of fasteners or securing devices including straps or bands may also
be used for attaching the photocell device 172 to such as an
externally facing side of a building.
It is contemplated that the photocell device 172 may be secured at
an outdoor location in a number of different manners, including
among those the use of the turf stakes or fasteners. Output line
182 interconnects the transformer 174 with the photocell device 172
at any desired point between the transformer 174 and a first of the
lighting units 176 and 178. Alternate variants may further be
employed for transmitting the exterior light conditions to the
photocell unit within the device 172 and these include the
provision of the light permissive window 181 or the transparent rod
(at 183 in phantom) extending from a top surface of device 172.
Referring finally to FIG. 13, a yet further variation 184 of the
photocell device is illustrated and, similar to the disclosure
pertaining to the earlier embodiments of FIGS. 1-5, and includes in
one operative illustration, a turf stake 186 with downwardly
tapered portions 188, pointed end 190 and externally threaded screw
portions 192 at a corresponding upper end which engage within a
likewise shaped interiorly threaded recess (hidden from view)
forming a portion of an enclosure unit 194. As an alternative to
the transparent rod or exteriorly mounted photo sensor element (see
at 52 in FIG. 4) one or more transparent or light permissive
windows may be located upon a forwardly facing surface 196 and/or
top surface 198 of the enclosure unit 194. The photocell assembly,
substantially as previously described, is contained within the
enclosure unit and is positioned so as to be proximate to either or
both the windows on the front 196 and/or top 198 surfaces and to
permit the device to adequately gauge outdoor light conditions.
In addition to the capabilities previously described, the photocell
device of the present invention can be programmed to turn on at
dusk and off based upon a number of different factors including
sunrise and sunset tables, the length of time the photocell is on
or off, whether the days are getting longer or shorter, whether
daylight savings time is in effect, the city or area of product
installation so as to determine longitude and latitude, and the
desired user designated off time. A suitable software algorithm
(not shown) is programmed into the control unit to determine the
amount of time the load is on to approximate the desired off time.
Without knowledge of real time, the photocell device would control
the desired off time of the load within a plus or minus of 3/4 of
an hour thus eliminating the need for most seasonal or real time
adjustments. Additional real time signalling inputs may also be
provided by broadcast digital time codes transmitted via radio
frequency from several different time and frequency stations
including satellites. Since the remote photocell would always know
real time (even after power outages) seasonal adjustments to the
off time of the lighting load would never be required.
It is therefore evident that the photocell device of the present
invention is a dramatic improvement over the limitations of prior
lighting assemblies. The photocell device can be used with any new
or existing lighting system and, due to its ability to connect to
the output line of the transformer at a location remote from the
transformer, enables greater flexibility of applications than
previously made possible by the prior art.
Having described my invention, additional embodiments will become
apparent to those skilled in the art to which it pertains without
deviating from the scope of the appended claims:
* * * * *